The standard routine practice in the vast majority of laboratories is to sterilize the microbiological and bacteriological culture media by the heating process called "autoclaving". Autoclaving is a form of "pressure-cooking" by which the nutrients or media are subjected to "trapped" or pressurized steam in a sturdy vessel "autoclave" or "pressure cooker" usually under a pressure of 15 lb/square inch to produce a temperature of approximately 121.degree. C. for about 20 minutes exposure of the medium to this "superheated steam" ensures or guarantees the destruction or annihilation of all forms of life: vegetative and otherwise (e.g. heat-resistant spores). The drawbacks or disadvantages of this widely used method of sterilizing culture media, include:
1. Caramelization. PA1 2. pH Changes PA1 3. Protein desintegration, denaturation and/or breakdown. PA1 4. Inactivation of certain vitamins and growth-promoting factors. PA1 5. Clouding and adverse effects on the optical clarity of the medium. PA1 6. Possible undesirable physical and/or chemical actions and interactions that may take place by and among the different ingredients of the medium PA1 7. Agar agar hydrolysis PA1 8. Frequency of failures, errors, hazards and accidents related to heat sterilization equipment i.e. the autoclave. PA1 9. Time consuming PA1 from 0.1% to 4% of a gelling agent; PA1 from 0.015% to 0.03% of a sterilizing agent PA1 from 7% to 50% of a nutrient concentrate, preferably, cold concentrated nutrients. The preferred amount is from 7 to 14% and a more preferred amount ranges from 7 to 10%.
There is accordingly a need for a culture medium which will obviate the aforementioned drawbacks of the prior art and which will have a long shelf life.
The main object of this invention is to provide such a medium.